<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var cup1 = '雪碧' //本身是雪碧  // ' 可乐'
        var cup2 = '可乐' //本身是可乐  // ' 雪碧'
        // 交换杯子1和2中的饮料
        var cup3 = '';    // ' '
        cup3 = cup1;
        cup1 = cup2; 
        cup2 = cup3;
        console.log(cup1,cup2)
    </script>
</body>
</html>